Method for fullerene derivative and the fullerene derivative proton conductor and electrochemical device

ABSTRACT

Provided are a method of efficiently procuding fullerene into which a OH group or a SO 3 H group is introduced, such as fullerenol, or a derivative thereof, the fullerene and its derivative being preferable as a proton conductor, and a novel and usable proton conductor obtained by the method. Further, provided is an electrochemical device using the proton conductor such as a fuel cell or the like. In the producing method of the fullerene derivative, halogated fullerene, which is obtained through halogating a fullerene molecule is used as a precursor, the fullerene derivative is produced through introducing one or more proton dissociative group into at least one carbon atom of a fullerene molecule. Moreover, in a producing method of a polymerized fullerene derivative, a plurality of fullerene derivatives are bonded to one another by an aromatic group of an aromatic compound through reacting the plurality of fullerene derivatives with the aromatic compound. The fullerene derivative obtained by any of these method functions as a proton conductor, and an electrochemical device using the proton conductor such as a fuel cell can be downsized and simplified without atmosphere constraints.

TECHNICAL FIELD

[0001] The present invention relates to a producing method of afullerene derivative suitable for a proton (hydrogen ion; H⁺) conductingmaterial, the fullerene derivative, a proton conductor, and anelectrochemical device.

BACKGROUND ART

[0002] Fullerene molecules C₆₀, and C₇₀ shown in FIGS. 15A and 15B werefound in a mass spectrometry spectrum of a cluster beam by laserablation of carbon in 1985 (Kroto, H. W.; Heath, J. R.; O'Brien, S. C.;Curl, R. F.; Smalley, R. E. Nature 1985.318,162.), and 5 years later in1990, a producing method of the fullerene molecules by arc dischargemethod using a carbon electrode was established. Since then, attentionhas been focused on the fullerene molecules as a carbon-basedsemiconductor material or the like.

[0003] Moreover, the first example of synthesis of an compound with astructure in which a plurality of hydroxyl groups are added to at leastone carbon atom of a fullerene molecule, that is, polyhydroxylatedfullerene (which is commonly called “fullerenol”, hereinafter referredto as fullerenol) was reported in 1992 by Chiang et al. (Chiang, L. Y.;Swirczewski, J. W.; Hsu, C. S.; Chowdhury, S. K.; Cameron, S.; Creegan,K. J. Chem. Soc, Commun. 1992,1791 and Chiang, L. Y; Wang, L. Y.;Swirczewski, J. W.; Soled, S.; Cameron, S. J. Org. Chem. 1994,59,3960).Since then, attention has been focused on fullerenol into which acertain amount or over of the hydroxyl groups is introduced,specifically its water-soluble property, and the fullerenol has beenstudied mainly in technical fields related to biotechnology.

[0004] Further, a compound in which the hydroxyl groups of theabove-described fullerenol was replaced with sulfone groups, that is,hydrogensulfate-esterified fullerenol was reported in 1994 by Chiang etal. (Chiang, L. Y.; Wang, L. Y.; Swirczewski, J. W.; Soled, S.; Cameron,S. J. Org. Chem. 1994,59,3960).

[0005]FIG. 16 shows an example of a conventionally known method ofsynthesizing the fullerenol and the hydrogensulfate-esterifiedfullerenol.

[0006] In the conventionally known synthesizing method (Long Y. Chianget al. J. Org. Chem. 1994,59,3960), fuming sulfuric acid is added to thefullerene molecule, then the fullerene molecule is hydrolyzed so as toobtain fullerenol C₆₀(OH)_(n). When the fullerenol reacts with sulfuricacid, hydrogensulfate-esterified fullerenol C₆₀(OSO₃H)_(n) is produced.

[0007] In recent years, for example, as a solid high molecular weightelectrolyte type fuel cell for a vehicle's power source, a fuel cellusing a proton (hydrogen ion; hereinafter referred to as the same)conducting high molecular weight material such as perfluorosulfonic acidresin (Nafion(R) of Du Pont or the like) is well known.

[0008] Moreover, as a relatively novel proton conductor, a polymolybdicacid containing a large amount of hydrated water such asH₃Mo₁₂PO₄₀.29H₂O, or an oxide containing a large amount of hydratedwater such as Sb₂O₅.5.4H₂O or the like is well known.

[0009] When the high molecular weight material and the hydratedcompounds are placed in a wet state, they exhibit high protonconductivity at about room temperature. In other words, when theperfluorosulfonic acid resin is taken as an example, protons ionizedfrom a sulfonic acid group of the perfluorosulfonic acid resin arebonded (hydrogen-bonded) to water contained in, for example, a highmolecular weight matrix of the solid high molecular weight electrolytein a large amount, to produce protonated water, that is, oxonium ions(H₃O⁺), and protons in the form of oxonium ions can smoothly move in thehigh molecular weight matrix, so a matrix material of this kind canexert a very high proton conduction effect even at room temperature.

[0010] On the other hand, recently, a proton conductor with a conductionmechanism completely different from those of the above proton conductorshas been also developed. More specifically, it has been found that acomposite metal oxide with a perovskite structure such as SrCeO₃ dopedwith Yb or the like can conduct protons without using water as atransfer medium. It has been considered that in the composite metaloxide, protons are singly channeled between oxygen ions forming aframework of the perovskite structure so as to be conducted.

[0011] In this case, conductive protons are not originally present inthe composite metal oxide. When the perovskite structure is in contactwith water vapor contained in an ambient atmospheric gas, watermolecules at high temperature react with an oxygen deficient portionformed in the perovskite structure by doping, and the protons aregenerated only by the reaction.

[0012] However, the above described various proton conductors have thefollowing problems.

[0013] Firstly, in order to maintain high proton conductivity, thematrix material such as the perfluorosulfonic acid resin is required tobe continuously placed in a wet state during use. Therefore, ahumidifier or various accompanying apparatuses are required to bemounted in the entire structure of a system such as fuel cell or thelike, so an increase in the size of the system and cost for systemconfiguration is inevitable.

[0014] Moreover, the operating temperature of the system is limited to arange in which freezing and boiling of water contained in the matrix donot occur, so there is a problem that it is difficult to have a widertemperature range.

[0015] Further, in the case of the composite metal oxide with theperovskite structure, in order that meaningful proton conduction iscarried out, the operating temperature is required to be maintained at500° C. or over.

[0016] As described above, the conventional proton conductors have thefollowing problems. The conventional proton conductor has highdependence on atmosphere, and more specifically, moisture must besupplied to the proton conductor, or the proton conductor requires watervapor. Further, the range of the operating temperature is narrow, or theoperating temperature is too high.

[0017] Therefore, the applicant of the present invention has found that,as described above, fullerenol and hydrogensulfate-esterified fullerenolexhibit proton conductivity, and has proposed novel proton conductors(hereinafter referred to as inventions disclosed in the priorapplications) in Japanese Patent Application No. Hei 11-204038 and2000-058116.

[0018] The proton conductors according to the inventions disclosed inthe prior applications can be used in a wide temperature range includingroom temperature, and a lower limit of the temperature range is notspecifically high. Further, the proton conductors do not require wateras a transfer medium. Therefore, the proton conductors have achieved areduction in dependence on atmosphere, and an increase in an applicablerange.

[0019] There are two following factors which control proton conductivityof fullerenol and hydrogensulfate-esterified fullerenol.

[0020] One of the factors is a structural aspect. It is considered thata proton transfer phenomenon occurs by quantum channeling effects, sofullerenol and hydrogensulfate-esterified fullerenol preferably have atightly packed solid structure, because (1) the quantum channelingeffects are highly dependent on a distance between each site whichtransfers protons, (2) when fullerenol and hydrogensulfate-esterifiedfullerenol have a tightly packed solid structure, a more stable thinfilm can be formed, thereby a thinner layer with high conductance can besupplied, and (3) a loss of H₂ in a proton conducting layer is reducedby diffusion of H₂.

[0021] The other factor is the number of sites which transfer protons.An important factor which controls conductance is the number of chargedcarriers which can be used for proton transfer. Therefore, animprovement in proton conductance can be expected by increasing thenumber of proton transfer sites in the proton conducting layer.

[0022] However, in the above-described conventional method ofsynthesizing fullerenol and hydrogensulfate-esterified fullerenol, thefollowing problems arise. Namely, when the hydroxyl groups are added toa fullerene molecule, the position of the hydroxyl groups introducedinto at least one carbon atom of the fullerene molecule cannot becontrolled, and the number of the hydroxyl groups introduced into thefullerene molecule cannot be controlled (12 hydroxyl groups perfullerene molecule is a limit).

[0023] In view of the foregoing, it is a first object of the inventionto provide a method of efficiently producing fullerene into which ahydroxyl group is introduced and which is suitable as a protonconductor, such as fullerenol, or a derivative thereof.

[0024] It is a second object of the invention to provide a novel anduseful fullerene derivative obtained by the method, a proton conductor,and an electrochemical device using the proton conductor.

DISCLOSURE OF THE INVENTION

[0025] The present invention provides a producing method of a fullerenederivative (hereinafter referred to as a first producing method of theinvention), which comprises the steps of reacting a fullerene moleculewith at least one halogen atom so as to produce a halogenated fullerene;and

[0026] reacting the halogenated fullerene with a hydroxide or sulfite soas to produce a fullerene derivative, wherein one or more proton (H⁺)dissociative group is introduced into at least one carbon atom of thefullerene molecule.

[0027] The invention also provides a producing method of a fullerenederivative (hereinafter referred to as a second producing method of theinvention), which comprises the steps of reacting a fullerene moleculewith at least one halogen atom so as to produce halogenated fullerene;and reacting the halogenated fullerene with an aromatic compound havingone or more proton (H⁺) dissociative group by exchange reactionspecifically in the presence of a Lewis acid catalyst so as to produce afullerene derivative, wherein one or more aromatic group having one ormore proton (H⁺) dissociative group is introduced into at least onecarbon atom of the fullerene molecule.

[0028] Herein, “a proton dissociative group” in the invention means afunctional group in which a proton can be dissociated by ionization, and“proton (H⁺) dissociation” means that a proton is dissociated from thefunctional group by ionization.

[0029] According to the first and the second producing methods of theinvention, halogenated fullerene as a precursor is produced by areaction between a fullerene molecule and halogen, and by use of theprecursor, a fullerene derivative such as fullerenol is produced.Therefore, compared to a method of directly synthesizing fullerenol froma fullerene molecule, such as the above described conventionally knownmethod, while dependence on properties of halogen and its position areexhibited, the number of hydroxyl groups added to the fullerene moleculeor the positions of the hydroxyl groups can be controlled, thereby, aderivative suitable for proton conducting material can be obtained.

[0030] In addition, by using the above halogenated fullerene, the numberof the above introduced group in an aromatic compound which will bereacted with the halogenated fullerene can be increased, sohydroxylation of fullerene or the like can be carried out to a highdegree. Thereby, the number of charged carriers which can be used forproton transfer can be increased, and the number of proton transfer (ormigration) site can be increased, and accordingly, proton conductancecan be improved.

[0031] The invention provide a producing method of a polymerizedfullerene derivative (hereinafter referred to as a third producingmethod of the invention), which comprises the steps of: reacting afullerene molecule with at least one halogen atom so as to producehalogenated fullerene; reacting the halogenated fullerene or aderivative thereof with a first aromatic compound having one or moreproton (H⁺) dissociative group and a second compound by exchangereaction especially in the presence of a Lewis acid catalyst so as toproduce a fullerene derivative, wherein one or more aromatic group ofthe first aromatic compound having one or more proton (H⁺) dissociativegroup is introduced into at least one carbon atom of the fullerenemolecule; and bonding a plurality of the fullerene derivatives obtainedthereby to one another by one or more aromatic group of the secondaromatic compound so as to produce a polymerized fullerene.

[0032] According to the third producing method of the invention, as inthe case of the first and the second producing methods of the invention,by using the halogenated fullerene, the aromatic compound having theproton (H⁺) dissociative group is introduced into the fullerenemolecule, and the fullerene is polymerized through bonding fullerenemolecules to one another by the aromatic group, so while the positionsand the number of transfer sites for proton conduction are preferablycontrolled, a decline in the strength of the fullerene derivative due toaddition of a group such as a hydroxyl group can be fully compensated bypolymerization, therefore, a thin film with larger strength can beformed.

[0033] The invention related to a fullerene derivative (hereinafterreferred to as a first fullerene derivative of the invention), whereinone or more aromatic group having a proton (H⁺) dissociative groupintroduced into at least one carbon atom of a fullerene molecule.

[0034] As described above, in the first fullerene derivative of theinvention, the proton dissociative group is introduced by the aromaticgroup, so the number of proton transfer sites can be increased, and thepositions of proton transfer sites can be controlled.

[0035] The invention provides a polymerized fullerene derivative(hereinafter referred to as a second fullerene derivative of theinvention), wherein in a fullerene derivative, one or more firstaromatic group having one or more proton (H⁺) dissociative group isintroduced in at least one carbon atom of a fullerene molecule, and aplurality of the fullerene derivatives are bonded to one another by asecond aromatic group so as to produce a polymerized fullerenederivative.

[0036] In other words, in the second fullerene derivative of theinvention, in addition to having advantages of the first fullerenederivative of the invention, the fullerene molecule is polymerized, so athin film with larger strength as described above can be formed.

[0037] The first and the second fullerene derivatives can form a firstproton conductor and a second proton conductor of the invention,respectively. The first proton conductor of the invention can besubstantially formed of the fullerene derivative only in a thin filmthrough, for example, compression molding, or can be formed of fullerenederivatives bonded by a binder in a thin film. Moreover, the secondproton conductor of the invention uses the polymerized fullerenederivative, so the proton conductor has been already polymerized.Therefore, the proton conductor can be formed in a thin film with largerstrength without using a binder.

[0038] In the first and the second fullerene derivatives of theinvention and the first and the second proton conductors of theinvention, as in the case of the above-described inventions disclosed inthe prior applications, the proton dissociative group is introduced intothe fullerene molecule, so they become proton conductors with smalleratmosphere dependence, which can be used within a wider temperaturerange including room temperature and have the lower limit being notspecifically high, and which do not require water as a transfer medium(however, water may be present therein).

[0039] The invention further provides an electrochemical device(hereinafter referred to as an electrochemical device of the invention),which comprises a first electrode, a second electrode and a protonconductor sandwiched between the first electrode and the secondelectrode, wherein the proton conductor comprises either the following(1) or (2).

[0040] The proton conductor comprises (1) a fullerene derivative as amain component, wherein one or more aromatic group having one or moreproton (H⁺) dissociative group is introduced into at least one carbonatom of a fullerene molecule (that is, the first proton conductor of theinvention).

[0041] Alternatively, the proton conductor comprises (2) a polymerizedfullerene derivative, wherein in a fullerene derivative, one or morefirst aromatic group having one or more proton (H⁺) dissociative groupis introduced in at least one carbon atom of a fullerene molecule, and aplurality of the fullerene derivatives are bonded to one another by asecond aromatic group so as to produce the polymerized fullerenederivative (that is, the second proton conductor of the invention).

[0042] Thus, the electrochemical device of the invention comprising thefirst or the second proton conductor of the invention is not subject toatmosphere constraints, so downsizing and simplification of the systemthereof can be achieved.

[0043] Other and further objects, features and advantages of theinvention will appear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044]FIG. 1 shows a first producing method and a second producingmethod of the invention and examples of a fullerene derivative obtainedby the methods;

[0045]FIGS. 2A through 2D are illustrations showing the first producingmethod of the invention and examples of a fullerene derivative obtainedby the first producing method;

[0046]FIGS. 3A through 3C are illustrations showing examples offluorinated fullerene as halogenated fullerene (precursor) in the firstproducing method of the invention;

[0047]FIGS. 4A through 4C are illustrations showing the first producingmethod of the invention and examples of the fullerene derivativeobtained by the first producing method;

[0048]FIG. 5 is an illustration showing a third producing method of theinvention and an example of a polymerized fullerene derivative obtainedby the third producing method;

[0049]FIGS. 6A and 6B are schematic views showing examples of a protonconductor of the invention;

[0050]FIG. 7 is an illustration showing the structure of a fuel cellaccording to an embodiment of the invention;

[0051]FIG. 8 is a sectional view of the fuel cell shown in FIG. 7;

[0052]FIGS. 9A and 9B are schematic diagrams of an equivalent circuit ofthe fuel cell shown in FIG. 7;

[0053]FIG. 10 is a graph showing a result of measuring the compleximpedances of a fullerene derivative aggregate pellet used in FirstExample of the invention;

[0054]FIG. 11 is a graph showing temperature dependence of protonconductivity of the aggregate pellet shown in FIG. 10;

[0055]FIG. 12 is an illustration showing the structure of a hydrogen-aircell according to the embodiment of the invention;

[0056]FIG. 13 is a schematic view showing the structure of anelectrochemical device according to another embodiment of the invention;

[0057]FIG. 14 is a schematic view showing the structure of anelectrochemical device according to still another embodiment of theinvention;

[0058]FIGS. 15A and 15B are structure diagrams of a fullerene molecule;and

[0059]FIG. 16 is an illustration showing a conventionally knownproducing method of a fullerene derivative.

BEST MODE FOR CARRYING OUT THE INVENTION

[0060] In the present invention, a fullerene molecule as a base intowhich one or more proton dissociative groups are introduced is notspecifically limited, as long as the fullerene molecule is a sphericalcarbon cluster molecule Cm. However, in general, a fullerene moleculeselected from the group of fullerene molecules C₃₆, C₆₀ (refer to FIG.15A), C₇₀ (refer to FIG. 15B), C₇₆, C₇₈, C₈₀, C₈₂, C₈₄ and so on or amixture of two or more kinds selected from the fullerene molecules ispreferably used.

[0061] Next, examples of a fullerene derivative of the invention and aproducing method thereof will be described below.

[0062]FIG. 1 shows an example of a first producing method of theinvention. In the method, for example, a fullerene molecule (forexample, C₆₀) is reacted with at least one halogen atom X to producehalogenated fullerene C₆₀X_(n), and the halogenated fullerene is reactedwith hydroxide MOH (that is, nucleophilic substitution reaction) so asto produce a fullerene derivative (C₆₀(OH)_(n), C₆₀(OSO₃H)_(n) which isC₆₀(OH)_(n) sulfonated by sulfuric acid, or the like) having one or moreproton dissociative group (for example, —OH, —OSO₃H, —SO₃H or the like)in at least one carbon atom of the fullerene molecule, as a protonconductor.

[0063] Moreover, in the first producing method (not shown) according tothe invention, for example, C₆₀X_(n) as the above-described halogenatedfullerene and sulfite M₂SO₃ are reacted with each other so as to producea fullerene derivative (for example, C₆₀(SO₃H)_(n) or the like) havingone or more SO₃H group as the proton dissociative group in at least onecarbon atom of the fullerene molecule, as a proton conductor.

[0064] As the halogen atom X used herein, a halogen atom selected fromthe group consisting of a fluorine atom (F), a chlorine atom (Cl) and abromine atom (Br) are preferable (hereinafter the same). These halogenatoms can be supplied by a fluorine compound, bromine or the like, asdescribed later.

[0065] As the above-described halogenated fullerene, brominatedfullerene, chlorinated fullerene and fluorinated fullerene are listed inorder of increasing stability and increasing solubility.

[0066] As the halogenated fullerene, fluorinated fullerene andchlorinated fullerene are more preferably used as a precusor. Fluorinatefullerene or chlorinated fullerene easily induces a nucleophilicsubstitution reaction, and the order of decreasing nucleophilicsubstitution reactivity is C—F>C—Cl>C—Br. It is effective to determinereaction conditions based upon such reactivity, because the structure offullerenol or a derivative thereof can be determined depending upon thekind of a precursor of each halogenated fullerene.

[0067]FIGS. 2A through 2D show examples of halogenation of a fullerenemolecule, and show examples of chlorinated fullerene and brominatedfullerene, that is, C₆₀Cl₆, C₆₀Br₆, C₆₀Br₈, C₆₀Cl₂₄ and C₆₀Br₂₄. FIGS.3A through 3C show examples of fluorinated fullerene, that is, C₆₀F₁₈,C₆₀F₃₆ and C₆₀F₄₈ (in the case of C₇₀, C₇₀F₃₆₋₄₀ in general). Some ofthese halogenated fullerenes are produced as a main component, but ingeneral, the halogenated fullerenes are produced as a mixture.

[0068] M in the above hydroxide MOH or the above sulfite M₂SO₃ ispreferably an alkali metal atom selected from the group consisting ofLi, Na and K.

[0069] A reaction between the above halogenated fullerene and the abovehydroxide is preferably carried out in an inert organic solvent such aso-dichlorobenzene or the like, and the above organic solvent to which atleast one of crown ether and a Lewis acid catalyst (AlCl₃, FeCl₃, TiCl₄or the like) is added is more preferable. As the above Lewis acidcatalyst, a catalyst selected from the group consisting of AlCl₃, FeCl₃and TiCl₄ can be used.

[0070] Moreover, the reaction between the above halogenated fullereneand the above hydroxide can be carried out in a two-phase system of theabove hydroxide solution and the above organic solvent by using at leastone of a phase-transfer catalyst such as NBu₄OH or the like and theLewis acid catalyst (the same as above) at room temperature or a raisedtemperature. In some cases (for example, in the case where fluorinatedfullerene is used), hydroxylation can be carried out through reactingwith water.

[0071] Further, hydroxylated fullerene (fullerenol) can be obtained by areaction between the above halogenated fullerene and the abovehydroxide, and the hydroxylated fullerene can be further sulfonated(—OSO₃H can be introduced into the hydroxylated fullerene) by sulfuricacid, or phosphatized (—OPO(OH)₂ can be introduced into the hydroxylatedfullerene) by phosphoric acid. The sulfonated fullerene has an advantagethat the sulfonated fullerene has higher proton conductivity thanfullerenol.

[0072] Further, an example of a first fullerene derivative (or a firstproton conductor) obtained by a second producing method of the inventionas described above is also shown in FIG. 1.

[0073] The second producing method of the invention is a producingmethod of a fullerene derivative as a proton conductor, in which by anucleophilic substitution reaction between the halogenated fullereneproduced based upon the above-described first producing method of theinvention and an aromatic compound having one or more protondissociative group, one or more aromatic group having the above protondissociative group is introduced into at least one carbon atom of theabove fullerene molecule.

[0074] A Lewis acid catalyst which can be used in the second producingmethod of the invention is not specifically limited, and, for example, acatalyst selected from the group consisting of AlCl₃, FeCl₃ and TiCl₄ iscited. In the presence of the Lewis acid catalyst, the halogenatedfullerene forms a carbocation, and an electrophilic substitutionreaction between the carbocation and an aromatic compound such as phenolor the like can occur. The substitution reaction selectively occurs in aposition where the halogen atom of the fullerene molecule is introduced,and aromatic group substituted fullerene corresponding to halogenatedfullerene can be reliably obtained.

[0075] The above group which can dissociate the above proton may beselected from the group consisting of —OH, —OSO₃H, —COOH, —SO₃H and—OPO(OH)₂ (hereinafter the same).

[0076] The above aromatic compound or a mixture of the aromatic compoundand other solvent (for example, o-dichlorobenzene) can be used as asolvent.

[0077] Moreover, the above aromatic group added to the fullerenemolecule may be, for example, an aryl group such as a phenol group, andan aromatic compound having one, or two or more hydroxyl groups in onearomatic ring (for example, resorcinol) may be used. When an aromaticcompound having two or more hydroxyl groups or the like is used, protontransfer sites can be easily increased.

[0078]FIG. 4A shows an example of the second producing method of theinvention and C₆₀(Ar—OH)₅Cl which can be obtained thereby, and FIGS. 4Band 4C show C₇₀(Ar—OH)₁₀ and C₆₀(Ar—OH)₁₈ which can be obtained in thesame manner, respectively. For example, phenolated fullerene can befurther sulfonated by sulfuric acid, as shown in FIG. 1.

[0079]FIG. 5 shows a third producing method of the invention and anexample of a second fullerene derivative (a second proton conductor)which can be obtained thereby.

[0080] The third producing method of the invention is a mehtod ofproducing a polymerized fullerene derivative as a proton conductor, inwhich by a reaction among halogenated fullerene which is produced basedon the above first producing method of the invention, a first aromaticcompound having one or more proton dissociative group and a secondaromatic compound (specifically in the presence of the Lewis acidcatalyst), one or more aromatic group of the first aromatic compoundhaving the proton dissociative group is introduced into at least onecarbon atom of the fullerene molecule, and a plurality of fullerenederivatives obtained thereby are bonded to one another through anaromatic group of the above second aromatic compound (introduction ofthe aromatic group by the same nucleophilic substitution reaction as theabove).

[0081] In the third producing method of the invention, the abovereaction can occur in a common system (for example, in a singlecontainer), and the number of proton transfer sites in the fullerenederivative obtained by polymerization can be determined by a ratio ofthe first and the second aromatic compounds. Moreover, the thirdproducing method may adopt a two-step reaction in which a reactionbetween the above halogenated fullerene and the above first aromaticcompound is carried out at first (in this case, a predetermined numberof halogen atoms required for a polymer are left in the fullerenemolecule), and then a reaction with the above second aromatic compoundis carried out to produce the polymerized fullerene derivative.

[0082] Further, a Lewis acid catalyst used in the producing method isnot specifically limited, and, for example, a catalyst selected from thegroup consisting of AlCl₃, FeCl₃ and TiCl₄ is cited.

[0083] As the above first aromatic compound, an aryl compound such asphenol may be used, and an aromatic compound having one, or two or morehydroxyl groups or the like in one aromatic ring may be used. When anaromatic compound having two or more hydroxyl groups or the like (forexample, resorcinol) is used, proton transfer sites can be easilyincreased.

[0084] Moreover, the above first aromatic compound or a mixture of thefirst aromatic compound and other solvent (for example,o-dichlorobenzene) may be used as a solvent.

[0085] As the above second aromatic compound, an aromatic compoundrepresented by Chemical Formula 1 is preferably used. In ChemicalFormula 1, n, p and q are integers selected from the range from 0 to 5,and Ar¹ and Ar² are substituted or unsubstituted aryl groups which arethe same as or different from each other, and Y and Z are substitutedgroups which are the same as or different from each other, such as, forexample, the above-described proton dissociative hydroxyl group or thelike.

[0086] Moreover, a large number of the above fullerene derivatives canbe three-dimensionally bonded to one another by the aromatic group ofthe above second aromatic compound so as to be polymerized. Further, thestructure of the above second aromatic compound as a chain for bondingbetween the fullerene derivatives is not limited to the structure of anaromatic compound in which Ar¹ and Ar² are unsubstituted groups (forexample, benzene ring group) in Chemical Formula 1, and variousstructures such as, for example, a structure in which one or morehydroxyl groups are introduced into a benzene ring can be applicable. Inthe latter case, there is a possibility that proton transfer sites canbe increased even in the second aromatic compound by the hydroxyl groupsor the like.

[0087] As shown in FIGS. 1, 2A, 2B, 2C, 2D, 4A, 4B and 4C, the firstfullerene derivative of the invention obtained based on theabove-described second producing method of the invention is a fullerenederivative functioning as a proton conductor, which is produced throughintroducing one or more aromatic group having one or more protondissociative group into at least one carbon atom of a fullerenemolecule.

[0088] In the first fullerene derivative of the invention, the abovearomatic group may be an aryl group such as a phenol group, however,when an aromatic group having one, or two or more hydroxyl groups or thelike is used, proton transfer sites can be easily increased.

[0089] Moreover, the second fullerene derivative of the inventionobtained based on the third producing method of the invention is apolymerized fullerene derivative functioning as a proton conductor,which is produced through bonding a plurality of fullerene derivativesto one another by the second aromatic group, as shown in FIG. 5, theplurality of fullerene derivatives being produced through introducingthe first aromatic groups having the proton dissociative group into thecarbon atom of the fullerene molecule.

[0090] In the second fullerene derivative of the invention, the abovefirst aromatic group may be, for example, an aryl group such as a phenolgroup, however, when an aromatic group having one, or two or morehydroxyl groups or the like is used, proton transfer sites can be easilyincreased Moreover, the above second aromatic group is preferably anaromatic group represented by Chemical Formula 2. In Chemical Formula 2,n, p′ and q′ are integers selected from the range from 0 to 5, andAr^(1′) and Ar^(2′) are substituted or unsubstituted aromatic groupswhich are the same as or different from each other, and Y and Z aresubstituted groups which are the same as or different from each other,such as, for example, the above-described proton dissociative hydroxylgroup or the like.

[0091] Further, the structure of the above second aromatic group as achain for bonding between the fullerene derivatives is not limited tothe structure of an aromatic group in which Ar^(1′) and Ar^(2′) areunsubstituted groups (for example, benzene ring group) in ChemicalFormula 2, and various structures such as, for example, a structure inwhich one or more hydroxyl groups are introduced into a benzene ring canbe applicable. In the latter case, there is a possibility that protontransfer sites can be increased even in the second aromatic compound bythe hydroxyl groups or the like.

[0092] The above polymerized fullerene derivative is preferablypolymerized through three-dimensionally bonding a large number of theabove fullerene derivatives to one another by the above second aromaticgroup.

[0093] The number of the hydroxyl groups added to the first and thesecond fullerene derivatives of the invention, or the arrangement of thehydroxyl groups in the molecule can be variously modified, and thefullerene derivative having the hydroxyl groups can be furthersulfonated. The sulfonated fullerene derivative can be variouslymodified, such as a sulfonated fullerene derivative having a sulfonegroup only in one molecule, or a sulfonated fullerene derivative intowhich one, or a plurality of sulfone groups and one, or a plurality ofhydroxyl groups are introduced, or the like.

[0094] The first and the second proton conductors of the invention maysubstantially comprise the above fullerene derivative only, or maycomprise the fullerene derivatives bonded by a binder.

[0095] As shown in a schematic view of FIG. 6A, it has been found thatin an aggregate of fullerenol obtained based upon the first producingmethod of the invention, an interaction among hydroxyl groups offullerenol molecules adjacent to one another (in the drawing, ◯indicates a fullerene molecule) occurs, thereby the aggregate exhibitshigh proton conductivity (in other words, dissociation of H⁺ fromphenolic hydroxyl groups of the fullerenol molecules) as a macroaggregate.

[0096] Further, except for fullerenol, for example, a fullerenederivative having a plurality of sulfone groups shown in FIG. 6B can beused as an aggregate.

[0097] Moreover, the proton dissociative group of the invention is notlimited to the above hydroxyl group and the sulfone group, and isselected from the group consisting of —OH, —OSO₃H, —COOH, —SO₃H and—OPO(OH)₂, for example.

[0098] Further, in the invention, in order to produce a fullerenolderivative, the halogenated fullerene is used as a precursor, so a largenumber of proton dissociative groups which are at least one selectedfrom the group consisting of OH groups, SO₃H groups, aromatic groupscontaining hydroxyl groups and so on can be introduced into onefullerene molecule, thereby a number density of proton transfer sitesper volume in the proton conductor increases. Further, in order toexhibit dependence in properties of halogen, the number and the positionof added proton dissociative groups can be specifically determined.

[0099] Further, proton conductivity becomes more pronounced when sulfonegroups, instead of hydroxyl groups, are introduced into the carbon atomof the fullerene molecule.

[0100] When the number of the hydroxyl groups or the like added to thefullerene molecule increases, the proton conductivity of the obtainedfullerene derivative may become higher, and the strength thereof maybecome lower. However, as in the case of the second fullerene derivativeof the invention, when the fullerene derivative is polymerized, whilemaintaining high proton conductivity, the strength can be enhanced.

[0101] The first and the second proton conductors of the invention (thefirst and the second fullerene derivatives of the invention) can bepreferably used in various electrochemical devices.

[0102] In other words, the first or the second proton conductor can bepreferably used in a basic structure comprising a first electrode, asecond electrode and a proton conductor sandwiched between theelectrodes.

[0103] More specifically, the first or the second proton conductor ofthe invention can be preferably used in an electrochemical device inwhich at least one of the first electrode and the second electrode is agas electrode, or an electrochemical device in which at least one of thefirst electrode and the second electrode is an active materialelectrode.

[0104] In this case, it is preferable that the proton conductorsubstantially comprises the above fullerene derivative only, orcomprises the fullerene derivatives bonded by a binder.

[0105] An example of a fuel cell in which the proton conductorsubstantially comprising the above fullerene derivatives only is usedwill be described below.

[0106] Proton conduction in the fuel cell is as shown in a schematicview of FIG. 7. A proton conducting portion 1 is sandwiched between afirst electrode (for example, hydrogen electrode) 2 and a secondelectrode (for example, oxygen electrode) 3, and dissociated protonsmove from the first electrode 2 side to the second electrode 3 sidealong a direction indicated by an arrow in the drawing.

[0107]FIG. 8 shows a specific example of a fuel cell using the first orthe second proton conductor of the invention as a proton conductingportion.

[0108] The fuel cell comprises an anode (fuel electrode or hydrogenelectrode) 2 with a terminal 8 and a cathode (oxygen electrode) 3 with aterminal 9 which face each other, and catalysts 2 a and 3 b are incontact with or dispersed in the anode 2 and the cathode 3,respectively. A film-shaped proton conducting portion 1 which is formedthrough compression molding of the fullerene derivative is sandwichedbetween the anode 2 and the cathode 3.

[0109] During use of the fuel cell, on the anode 2 side, hydrogen issupplied from an inlet 12, and is discharged from an outlet 13 (which isnot provided in some cases). While fuel (H₂) 14 passes through a flowpath 15, protons are generated, and the protons move to the cathode 3side together with protons generated in the proton conducting portion 1.Then, the protons are reacted with oxygen (air) 19 which is suppliedfrom an inlet 16 to a flow path 17 so as to direct to an outlet 18.Thereby a desired electromotive force can be generated.

[0110] In the fuel cell with such a structure, while protons aredissociated in the proton conducting portion 1, protons supplied fromthe anode 2 side move to the cathode 3 side, so proton conductivitybecomes higher. Accordingly, no humidifier or the like is required,thereby simplification of the system and a reduction in the weight ofthe system can be achieved.

[0111] The second proton conductor of the invention comprises the abovepolymerized fullerene derivative, so the proton conductor has a filmforming ability, therefore the proton conductor can form the protonconducting portion without binder, and can overcome a film weakening dueto the hydroxyl groups or the like of the fullerene derivative. On theother hand, the first proton conductor of the invention can not onlyform a proton conducting portion through compression molding (aggregate)but also form a proton conducting portion with sufficient strengththrough bonding by a binder.

[0112] In this case, as a high molecular weight material which can beused as a binder, one kind, or two or more kinds of known polymershaving film-forming properties are used, and the binder content in theproton conducting portion is generally limited to 20 wt % or less. It isbecause when the content exceeds 20 wt %, proton conductivity maydecline.

[0113] The proton conducting portion with such a structure includes afullerene derivative as a proton conductor, so the same protonconductivity as that of the above-described proton conductorsubstantially comprising the fullerene derivative only can be exhibited.

[0114] In addition, unlike the case where the proton conductor comprisesthe fullerene derivative only, the proton conductor has film-formingproperties derived from the high molecular weight material, and theproton conductor can be used as a flexible proton conductive thin film(with a thickness of 300 μm or less, in general) having larger strengthand a gas penetration prevention function, compared to acompression-molded product made of powder of the fullerene derivative.

[0115] Further, the above high molecular weight material is notspecifically limited, as long as the high molecular weight materialcauses as little obstruction to proton conductivity (due to a reactionwith the fullerene derivative, or the like) as possible, and hasfilm-forming properties. In general, a high molecular weight materialhaving no electronic conductivity and having excellent stability isused. As specific examples of the high molecular weight material,polyfluoroethylene, polyvinylidene fluoride, polyvinyl alcohol and so onare cited, and they are preferable high molecular weight materialsbecause of the following reasons.

[0116] Firstly, polyfluoroethylene is preferable because, compared toother high molecular weight materials, a thin film with larger strengthcan be formed with a small amount of the polyfluoroethylene content. Thecontent in this case is as small as 3 wt % or less, preferably as smallas within a range from 0.5 wt % to 1.5 wt %, and the thin film can haveas thin a thickness as within a range from 100 μm to 1 μm in general.

[0117] Next, polyvinylidene fluoride and polyvinyl alcohol arepreferable because a proton conductive thin film having a superior gaspenetration prevention function can be formed by using polyvinylidenefluoride or polyvinyl alcohol. The content thereof in this case may bewithin a range from 5 wt % to 15 wt %.

[0118] In any case of polyfluoroethylene, polyvinylidene fluoride orpolyvinyl alcohol, the content thereof which is less than the lowerlimit of the range may adversely affect film formation.

[0119] In order to obtain a thin film of the proton conducting portionformed through bonding each fullerene derivative of the invention by abinder, a known method such as compression molding, extrusion molding orthe like may be used.

[0120]FIG. 12 shows a hydrogen-air cell to which the present inventionis applicable. In the hydrogen-air cell, a hydrogen electrode 21 and anair electrode 22 faces each other with a thin-film-shaped protonconductor (proton conductor made of the fullerene derivative of theinvention only or a mixture of the fullerene derivative of the inventionand a binder) 20 in between, and the outsides of the electrodes 21 and22 are sandwiched between a Teflon plate 24 a, and a Teflon plate 24 bwith a large number of holes 25. All components are fixed by the bolts26 a and 26 b and nuts 27 a and 27 b. A hydrogen electrode lead 28 a andan air electrode lead 28 b are laid from the hydrogen electrode 21 andthe air electrode 22, respectively, to outside.

[0121] Further, an electrochemical device shown in FIG. 13 can be usedas a secondary battery or the like, and the electrochemical device has astructure in which a proton conductor 34 is sandwiched between an anode31 having an anode active material layer 30 on an internal surfacethereof, and a cathode 33 (gas electrode) having a gas penetrationsupport 32 on an outer surface thereof. As the proton conductor 34, aproton conductor made of the fullerene derivative of the invention onlyor a mixture of the fullerene derivative of the invention and a binderis used. As an anode active material, a hydrogen absorbing alloy, or acarbon material such as fullerene supported by the a hydrogen absorbingalloy is preferable, and as the gas penetration support 32, for example,a porous carbon paper or the like is used. The cathode 33 is preferablyformed through coating with, for example, a material which is carbonpowder supported by platinum in paste form. Further, a space between theanode 31 and the cathode 33 is sealed by a gasket 35. In theelectrochemical device, water is present on the cathode 33 side so as tobe capable of charge.

[0122] Further, an electrochemical device shown in FIG. 14 can be usedas a secondary battery or the like, and the electrochemical device has astructure in which a proton conductor 41 formed through introducing abinder into each thin-film-shaped fullerene derivative of the inventionbetween an anode 38 having an anode active material layer 37 on aninternal surface thereof, and a cathode 40 having a cathode activematerial layer 39 on an internal surface thereof. As a cathode activematerial, for example, a material mainly containing nickel hydroxide isused. Further, in the electrochemical device, a space between the anode38 and the cathode 40 is sealed with a gasket 42.

[0123] Any of the electrochemical devices shown in FIGS. 12, 13 and 14can exert a proton conducting effect in the same mechanism as that ofthe electrochemical devices shown in FIGS. 7 and 8, which use the protonconductor substantially comprising each fullerene derivative of theinvention only. In addition, when the proton conductor comprises thefullerene derivative in combination with a high molecular weightmaterial having film-forming properties, the proton conductor can beused in a form of thin film with improved strength and small gaspermeability, so excellent proton conductivity can be exhibited.

[0124] The present invention will be described below with reference toExamples.

[0125] <Synthesis 1 of Halogenated Fullerene (Precursor)>

[0126] The synthesis of halogenated fullerene was carried out referringto a document of “Paul R. Birkett et al., Nature 1992,357,479”.

[0127] A fullerene molecule (C₆₀) and bromine (Br2) were reacted witheach other in carbon tetrachloride so as to produce a peach bloomcompound in a plate shape (a yield thereof was 92%). When the compoundwas subjected to a FT-IR measurement, the IR spectrum of the compoundnearly conformed to that of C₆₀Br₆ shown in the above document,therefore, it was confirmed that the compound was a target material,that is, brominated fullerene (C₆₀Br₆).

[0128] <Fullerene Derivative: Synthesis 1 of Polyhydroxylated Fullerene>

[0129] The halogenated fullerene (C₆₀Br₆) obtained by the above reactionwas reacted with hydroxide (NaOH) in an inert solvent which waso-dichlorobenzene (ODCB) with AlCl₃ as Lewis acid added thereto at roomtemperature so as to obtain polyhydroxylated fullerene (fullerenol)(C₆₀(OH)₆).

[0130] <Production 1 of Fullerene Derivative Aggregate Pellet>

[0131] Next, 90 mg of powder of fullerenol obtained by the abovereaction was pressed in one direction so as to be formed in a 15mm-diameter circular pellet. A pressing pressure at that time wasapproximately 7000 kg/cm². As a result, in spite of the fact that thefullerenol powder included no binder resin or the like, the powder hadexcellent moldability, so the powder could be easily pelletized. Thepellet had a thickness of approximately 300 μm (microns). The pellet wastaken as a pellet of Example 1.

[0132] <Synthesis 2 of Halogenated Fullerene (Precursor)>

[0133] The synthesis of halogenated fullerene was carried out referringto a document of “Olga V. Boltalina et al., J. Chem. Soc. Perkin Trans.2,1998,649”.

[0134] A mixture containing 25 mg of fullerene molecules (C₆₀) and 120mg of MnF₃ was introduced into a nickel tube (with a length of 30 mm anda diameter of 5 mm, one end thereof was closed), and then, the nickeltube was placed in a glass tube. The pressure in the glass tube wasreduced, and then the glass tube was filled with argon so that thepressure in the glass tube became 0.5 mbar. The glass tube was heated to350° C. within 30 minutes, and the temperature of the glass tube waskept at 350° C. for 24 hours. After that, the color of the material waschanged from a pale brown to nearly white through orange-yellow, so thematerial was cooled to obtain white powder. When the white powder wassubject to a FT-IR measurement, the IR spectrum of the white powdernearly conformed to that of C₆₀F₃₆ shown in the above document, so itwas confirmed that the white powder was a target material, that is,fluorinated fullerene (C₆₀F₃₆) (a yield thereof was 30%).

[0135] <Fullerene Derivative: Synthesis 2 of Polyhydroxylated Fullerene>

[0136] The above fluorinated fullerene (C₆₀F₃₆) was processed in thesame method as that of the above synthesis 1 of the fullerene derivativeso as to obtain corresponding polyhydroxylated fullerene (fullerenol)(C₆₀(OH)₃₆).

[0137] <Production 2 of Fullerene Derivative Aggregate Pellet>

[0138] In the same method as that of the above production 1 of thefullerene derivative aggregate pellet, fullerenol synthesized fromfluorinated fullerene was formed in a pellet with a thickness ofapproximately 300 μm. The pellet was taken as a pellet of Example 2.

[0139] <Fullerene Derivative: Synthesis 3 of Hydrogensulfate-EsterifiedFullerene (Whole Esterification)>

[0140] The synthesis was carried out referring to a document of “Chiang,L. Y.; Wang, L. Y.; Swirczewski. J. W.; Soled, S.; Cameron, S. J. Org.Chem. 1994,59,3960”.

[0141] After 1 g of powder of fullerenol obtained by the synthesis 1 ofthe fullerene derivative was put in 60 ml of fuming sulfuric acid, thepowder was stirred at room temperature in a nitrogen atmosphere forthree days. An obtained reactant was gradually put into anhydrousdiethyl ether cooled in a ice bath, and after an obtained deposit wasfractionated by centrifugal separation, and the deposit was cleaned withdiethyl ether three times and a 2:1 mixture of diethyl ether andacetonitrile two times, then the deposit was dried at 40° C. under areduced pressure. When powder thus obtained was subjected to a FT-IRmeasurement, the IR spectrum of the powder nearly conformed to that ofhydrogensulfate-esterified fullerenol in which all hydroxyl groups werehydrogensulfate-esterified, shown in the above document, so it wasconfirmed that the powder was a target material, that is, C₆₀(OSO₃H)₆.

[0142] <Fullerene Derivative: Production 3 of Hydrogensulfate-EsterifiedFullerene Aggregate Pellet>

[0143] Next, 70 mg of powder of hydrogensulfate-esterified fullerenolwas pressed in one direction so as to be formed in a 15 mm-diametercircular pellet. A pressing pressure at that time was approximately 7000kg/cm². As a result, in spite of the fact that the powder included nobinder resin or the like, the powder had excellent moldability, so thepowder could be easily pelletized. The pellet had a thickness ofapproximately 300 μm. The pellet was taken as a pellet of Example 3.

[0144] <Fullerene Derivative: Synthesis 4 of Hydrogensulfate-EsterifiedFullerene (Partial Esterification)>

[0145] After 30 ml of fuming sulfuric acid was added to 2 g of powder offullerenol obtained by the synthesis 1 of the fullerene derivative,hydroxyl groups contained in the fullerenol were partially esterified.

[0146] <Fullerene Derivative: Production 4 of Hydrogensulfate-EsterifiedFullerene Aggregate Pellet>

[0147] Next, 80 mg of powder of the partially hydrogensulfate-esterifiedfullerenol was pressed in one direction so as to be formed in a 15mm-diameter circular pellet. A pressing pressure at that time wasapproximately 7000 kg/cm². As a result, in spite of the fact that thepowder included no binder resin or the like, the powder had excellentmoldability, so the powder could be easily pelletized. The pellet had athickness of approximately 300 μm. The pellet was taken as a pellet ofExample 4.

[0148] <Synthesis 3 of Halogenated Fullerene (Precursor)>

[0149] The synthesis was carried out referring to a document of “Paul R.Birkett et al., J. Chem. Soc. Chem. Commun., 1995,683”.

[0150] A solution containing 150 mg of iodine-chloride in 5 ml of drybenzene was added to a solution containing 46.6 mg of fullerenemolecules (C₆₀) in 60 ml of dry benzene. The mixed solution was stirred,and was left standing for three days at room temperature. Next, asolvent and iodine were removed under a reduced pressure so as to leave60.7 mg of an orange microcrystalline solid. The product was cleanedwith pentane, and after cleaning, the product was heated to 60° C. Afterthe pressure was reduced to 0.1 mmHg, and the temperature of the productwas kept at the temperature for 5 hours, dark orange crystal wasobtained.

[0151] When the obtained crystal was subjected to a FT-IR measurement,the IR spectrum of the crystal nearly conformed to that of C₆₀Cl₆ shownin the above document, so it was confirmed that the crystal was a targetmaterial, that is, chlorinated fullerene (C₆₀Cl₆).

[0152] <Synthesis 5 of Fullerene Derivative>

[0153] The above obtained halogenated fullerene (C₆₀Cl₆) was reactedwith phenol (C₆H₅OH) in o-dichlorobenzene (ODCB) in the presence of aLewis acid catalyst (AlCl₃) at room temperature, and as a result, afullerene derivative C₆₀(C₆H₄OH)₅Cl or C₆₀(C₆H₄OH)₆ was obtained.

[0154] <Production 5 of Fullerene Derivative Aggregate Pellet>

[0155] Next, 90 mg of powder of the fullerene derivative was pressed inone direction so as to be formed in a 15 mm-diameter circular pellet. Apressing pressure at that time was approximately 7000 kg/cm². As aresult, in spite of the fact that the powder included no binder resin orthe like, the powder had excellent moldability, so the powder could beeasily pelletized. The pellet had a thickness of approximately 300 μm.The pellet was taken as a pellet of Example 5.

[0156] <Fullerene Derivative: Synthesis 6 of Hydrogensulfate-EsterifiedFullerene Derivative (Whole Esterification)>

[0157] When fuming sulfuric acid was added to the fullerene derivativeC₆₀(C₆H₄OH)₅Cl or C₆₀(C₆H₄OH)₆ obtained by the synthesis 5 of thefullerene derivative so that all hydroxyl groups added to the fullerenederivative were esterified, a hydrogensulfate-esterified fullerenederivative C₆₀(C₆H₄OSO₃H)₅Cl or C₆₀(C₆H₄OSO₃H)₆ was obtained.

[0158] <Fullerene Derivative: Production 6 of Hydrogensulfate-EsterifiedFullerene Derivative Aggregate Pellet>

[0159] Next, 70 mg of powder of the hydrogensulfate-esterified fullerenederivative was pressed in one direction so as to be formed in a 15mm-diameter circular pellet. A pressing pressure at that time wasapproximately 7000 kg/cm². As a result, in spite of the fact that thepowder included no binder resin or the like, the powder had excellentmoldability, so the powder could be easily pelletized. The pellet had athickness of approximately 300 μm. The pellet was taken as a pellet ofExample 6.

[0160] <Synthesis 7 of Fullerene Derivative>

[0161] The hologenated fullerene (C₆₀Cl₆) obtained by the abovesynthesis 5 of the halogenated fullerene precursor was reacted withresorcinol (C₆H₄(OH)₂) in o-dichlorobenzene (ODCB) in the presence of aLewis acid catalyst (AlCl₃) at room temperature. As a result, afullerene derivative C₆₀(C₆H₄(OH)₂)₅Cl or C₆₀(C₆H₄(OH)₂)₆ was obtained.

[0162] <Production 7 of Fullerene Derivative Aggregate Pellet>

[0163] Next, 90 mg of powder of the fullerene derivative was pressed inone direction so as to be formed in a 15 mm-diameter circular pellet. Apressing pressure at that time was approximately 7000 kg/cm². As aresult, in spite of the fact that the powder of the polyhydroxylatedfullerene included no binder resin or the like, the powder had excellentmoldability, so the powder could be easily pelletized. The pellet had athickness of approximately 300 μm. The pellet was taken as a pellet ofExample 7.

[0164] <Fullerene Derivative: Synthesis 8 of Hydrogensulfate-EsterifiedFullerene Derivative (Whole Esterification)>

[0165] When fuming sulfuric acid was added to the fullerene derivativeC₆₀(C₆H₄(OH)₂)₅Cl or C₆₀(C₆H₄(OH)₂)₆ obtained by the synthesis 6 of thefullerene derivative so that all hydroxyl groups added to the fullerenederivative were esterified, a hydrogensulfate-esterified fullerenederivative C₆₀(C₆H₄(OSO₃H)₂)₅Cl or C₆₀(C₆H₄(OSO₃H)₂)₆ was obtained.

[0166] <Production 8 of Hydrogensulfate-Esterified Fullerene DerivativeAggregate Pellet>

[0167] Next, 70 mg of powder of the hydrogensulfate-esterified fullerenederivative was pressed in one direction so as to be formed in a 15mm-diameter circular pellet. A pressing pressure at that time wasapproximately 7000 kg/cm². As a result, in spite of the fact that thepowder included no binder resin or the like, the powder had excellentmoldability, so the powder could be easily pelletized. The pellet had athickness of approximately 300 μm. The pellet was taken as a pellet ofExample 8.

[0168] <Synthesis 4 of Halogenated Fullerene (Precursor)>

[0169] After 1.76 g (2.445%10⁻³ mol) of fullerene molecules (C₆₀) werepulverized together with 10.9 g (9.405%10⁻² mol, 38.5 eq.) of CoF₃ and4.29 g (7.3%10⁻² mol) of Ni powder (Nilaco, with a particle diameterranging from 3 μm to 7 μm) in a box, an obtained mixture was put in astainless container. A sidewall of the stainless container could provideexcellent thermal contact. A hole with a diameter of 3 mm was disposedin the above container coated with a stainless sheet, and the containerwas placed in a quartz tube which had been heated to 50° C. Then, thepressure in the container was reduced to 0.05 mbar, and was heated to290° C. within 3 hours (1.3° C./min). When the temperature reached 280°C., 80 mbar of argon pressure was added. Next, when the temperaturereached 290° C., the temperature was further raised to 350° C. at a rateof 1° C./min. From the time when the temperature reached 290° C., areactant deposited in a cooled portion of the quartz tube could beobserved. Fourteen hours later, heating was stopped, and the temperatureof the above container decreased to room temperature, then the reactantdeposited in the container, that is, C₆₀F₄₀₋₄₄ was taken out. The abovereactant was a pale yellow or nearly white compound in a powder shape,and its yield was 1.38 g (37.2%).

[0170] A result of a spectroscopic analysis on the compound was shown asbelow.

[0171] Mass spectrum (MALDI-TOF,4-hydroxycinnamic acid, negative mode):1537.6(C₆₀F₄₃), 1518.5(C₆₀F₄₂), 1499.6(C₆₀F₄₁), 1461.5(C₆₀F₃₉),1423.5(C₆₀F₃₇), 1385.6(C₆₀F₃₅)

[0172] IR spectrum (KBr): 1621w, 1166.3(vs, (C—F)), 1134.1(vs, (C—F)),877.1(w), 571.1(w), 595.1(w)

[0173] Uv/Vis spectrum (methylene chloride): 325(sh)

[0174] <Synthesis 9 of Fullerene Derivative>

[0175] When C₆₀F₄₀₋₄₄ (1.37%10⁻³ mol) obtained by the same method asthat of the synthesis 4 of the halogenated fullerene was pulverizedtogether with 7.65 g (46 eq.) of Na₂SO₃ in the presence of argon in abox by a ball mill for 60 hours, a high water-soluble compound which wasnot dissolved in a solvent such as methanol or THF (tetrahydrofuran) wasobtained. In order to remove excess salt from the reaction mixture, thereaction mixture together with water as an eluate was purified through asilica-gel tower. After the reaction mixture was passed through a cationexchange device (manufactured by Mitsubishi Chemical America Inc., Daioncation exchange resin SK1B, with a column length of approximately 30cm), water was removed, and thereby, a compound C₆₀(SO₃H)_(n)F_(m) (n iswithin a range from 5 to 7, for example, 6, m is within a range from 10to 20, for example 15) in which a major portion of the solid was blackor dark brawn was obtained, and the product was dried in a vacuumchamber by an oil pump.

[0176] Moreover, the above obtained compound C₆₀(SO₃H)_(n)F_(m) wasfurther reacted with, for example, hydroxide (NaOH or the like) so thatC₆₀(SO₃H)_(n)(OH)_(m) as a fullerene derivative could be produced.Further, the above C₆₀(SO₃H)_(n)(OH)_(m) was esterified so thatC₆₀(SO₃H)_(n)(OSO₃H)_(m) or the like as a fullerene derivative could beproduced.

[0177] <Production 9 of Fullerene Derivative Aggregate Pellet>

[0178] Next, 90 mg of powder of the fullerene derivative was pressed inone direction so as to be formed in a 15 mm-diameter circular pellet. Apressing pressure at that time was approximately 7000 kg/cm². As aresult, in spite of the fact that the powder of the fullerene derivativeincluded no binder resin or the like, the powder had excellentmoldability, so the powder could be easily pelletized. The pellet had athickness of approximately 300 μm. The pellet was taken as a pellet ofExample 9.

[0179] <Synthesis 10 of Polymerized Fullerene Derivative>

[0180] Chlorinated fullerene C₆₀Cl₁₂ obtained by the same method as thatof the synthesis 3 of the halogenated fullerene was reacted with phenol(C₆H₄OH) and biphenyl in the presence of a Lewis acid catalyst (AlCl₃)in o-dichlorobenzene so that a polymerized fullerene derivative (apolymer in which C₆₀(C₆H₄OH)₈ as a monomer was bonded by biphenylgroups) was obtained. The polymerized fullerene derivative waspelletized, and the pelletized fullerene derivative was a pellet ofExample 10.

[0181] <Production of Fullerene Aggregate Pellet as Comparison>

[0182] For comparison, 90 mg of powder of fullerene C₆₀ used as asynthesis material in the above examples was pressed in one direction soas to be formed in a 16 mm-diameter circular pellet. A pressing pressureat that time was approximately 7000 kg/cm². As a result, in spite of thefact that the powder included no binder resin or the like, the powderhad excellent moldability, so the powder could be easily pelletized. Thepellet had a thickness of approximately 300 μm. The pellet was taken asa pellet of Comparative Example 1.

[0183] <Synthesis of Polyhydroxylated Fullerene as Comparison>

[0184] For comparison, based on a conventionally known synthesis method(refer to Long Y. Chiang et al. J. Org. Chem. 1994,59,3960), 2 g ofpowder of a C₆₀/C₇₀ fullerene mixture containing approximately 15% ofC₇₀ was put in 30 ml of fuming sulfuric acid, and the powder was stirredfor three days while being kept at 57° C. in a nitrogen atmosphere. Anobtained reactant was gradually put into anhydrous diethyl ether cooledin a ice bath, and after an obtained deposit was fractionated bycentrifugal separation, and the deposit was cleaned with diethyl etherthree times and a 2:1 mixture of diethyl ether and acetonitrile twotimes, then the deposit was dried at 40° C. under a reduced pressure.Further, the dried deposit was put in 60 ml of ion exchange water, andwas stirred for 10 hours at 85° C. through bubbling by nitrogen. After adeposit was fractionated by centrifugal separation, and was furthercleaned with pure water a few times, and centrifugal separation wasrepeated, the reactant was dried under a reduced pressure at 40° C. Whenbrawn powder thus obtained was subjected to a FT-IR measurement, the IRspectrum of the powder nearly conformed to that of C₆₀(OH)₁₂ shown inthe document, so it was confirmed that the powder was polyhydroxylatedfullerene (C₆₀(OH)₁₂).

[0185] <Production of Polyhydroxylated Fullerene Aggregate Pellet asComparison>

[0186] Next, 90 mg of powder of the polyhydroxylated fullerene waspressed in one direction so as to be formed in a 15 mm-diameter circularpellet. A pressing pressure at that time was approximately 7000 kg/cm².As a result, in spite of the fact that the powder included no binderresin or the like, the powder had excellent moldability, so the powdercould be easily pelletized. The pellet had a thickness of approximately300 μm. The pellet was taken as a pellet of Comparative Example 2.

[0187] <Proton Conductivity Measurement on Pellets Obtained in Examplesand Comparative Examples>

[0188] In order to measure conductivity of each pellet of Examples 1through 10 and Comparative Example 1, at first, the pellet was heldbetween aluminum plates with a diameter of 15 mm which was equivalent tothat of each pellet, and an AC voltage (amplitude: 0.1 V) at frequenciesranging from 7 MHz to 0.01 Hz was applied to the pellet so as to measurea complex impedance at each frequency. The measurement was carried outunder a dry atmosphere.

[0189] In relation to the impedance measurement, the proton conductingportion 1 of a proton conductor made of the above pellet electricallyconstituted an equivalent circuit as shown in FIG. 9A. In the equivalentcircuit, capacitors 6 and 6′ were formed between the first electrode 2and the second electrode 3 with the proton conducting portion 1indicated by a parallel circuit of a resistor 4 and a capacitor 5 inbetween. Further, as a delay effect (phase delay at high frequency)during proton transfer occurred by the capacitor 5, the capacitor 5indicated a parameter of proton transfer, and a proton transfer actionoccurred by the resistor 4, so the resistor 4 indicated a parameter ofmobility.

[0190] Herein, a measured impedance Z was represented byZ=Re(Z)+i·Im(Z), and frequency dependence of the proton conductingportion indicated by the above equivalent circuit was measured.

[0191] In addition, FIG. 9B shows an equivalent circuit using a typicalfullerene molecule without proton dissociation (Comparative Example 1).

[0192]FIG. 10 shows results of impedance measurement on pellets ofExample 1 and Comparative Example 1. In Comparative Example 1, frequencyproperties of the complex impedance were substantially the same as thebehavior of a single capacitor, so a transfer behavior of chargedparticles (such as electrons, ions or the like) was not observed at all.On the other hand, in Example 1, it was confirmed that in a highfrequency region of the impedance, a flattened but very smooth singlesemicircular arc was shown. It meant that some transfer behavior ofcharged particles occurred in the pellet. Further, in a low frequencyregion, a sharp rise in the imaginary part of the impedance wasobserved. It meant that blocking of charged particles between the pelletand an aluminum electrode occurred, as the voltage gradually became a DCvoltage. Herein, the charged particles on the aluminum electrode sidewere electrons, so it was found that the charged particles in the pelletwere not electrons nor holes, but other charged particles, that is,ions. According to the structure of fullerenol used at that time, it wasobvious that the charged particles were protons, but not any othercharged particles.

[0193] The conductivity of the charged particles could be determined byan X-axis intercept of the arc on the high frequency side. In the pelletof Example 1, the conductivity was approximately 5%10⁻⁶ sec./cm bycalculation. Moreover, when the pellets of Examples 2 through 10 weresubjected to the same measurement, the frequency properties of theimpedance in Examples 2 through 10 were similar in the whole shape tothose in Example 1. However, the conductivity of each of Example 2through 10 determined by an X-axis intercept of the arc was differentfrom others as shown in Table 1. Table 1 shows conductivity of eachproton conductor pellet according to the invention (at 25° C.), and, forexample, the conductivity was 5%10⁻² sec./cm in a wet state.

[0194] It was evident from Table 1 that when the hydroxyl groups werereplaced with OSO₃H groups or SO₃H groups, conductivity in the pellettended to increase, because hydrogen dissociation was more likely tooccur in the OSO₃H groups and the SO₃H groups than the hydroxyl groups.In any case of the hydroxyl groups, the OSO₃H groups and the SO₃Hgroups, or in a case where two of them were mixed, it was found thatprotons could be transferred in an aggregate of such a fullerenederivative in a dry atmosphere at room temperature.

[0195] Moreover, in Example 2, since, for example, OH groups wereexcessively introduced into at least one carbon atom of the fullerenemolecule, a resonance structure of the above fullerene moleculesometimes became unstable, and alcoholic properties increased. Thereby,the measurement of the conductivity could not be carried out in somecases.

[0196] Next, the pellet of Example 1 was subjected to the above compleximpedance measurement within a temperature range from 120° C. to −40° C.so as to determine temperature dependence of the conductivity determinedby an arc on the high frequency side. FIG. 11 shows the result as anArrhenius plot. As shown in FIG. 11, it was extremely obvious that theconductivity was linearly changed according to a change in temperaturefrom 120° C. to −40° C. It meant that a single ion conduction mechanismcould occur within the temperature range. In other words, the protonconductor of the invention could have conductivity even in a widetemperature range including room temperature, specifically at a hightemperature of 120° C. and a low temperature of −40° C.

[0197] As described above, in the producing method of the fullerenederivative of the invention, halogenated fullerene is used as aprecursor, so the number and the position of introduced protondissociative groups added to at least one carbon atom of a fullerenemolecule can be controlled, so a larger number of proton dissociativegroups can be introduced.

[0198] Moreover, the fullerene derivative obtained by the producingmethod of the fullerene derivative of the invention can exhibit higherproton conductivity, and the electrochemical device of the inventioncomprising the fullerene derivative is not subject to atmosphereconstraints, so downsizing and simplification of the system thereof canbe achieved.

[0199] Obviously many modifications and variations of the presentinvention are possible in the light of the above teachings. It istherefore to be understood that within the scope of the appended claimsthe invention may be practiced otherwise than as specifically described.

[0200] (CHEMICAL FORMULA 1)

[0201] FOR EXAMPLE,

[0202] (CHEMICAL FORMULA 2)

[0203] FOR EXAMPLE

TABLE 1 CONDUCTIVITY PELLET FULLERENE DERIVATIVE (sec./cm) Example 1C₆₀(OH)₆ 5% 10⁻⁶ Example 2 C₆₀(OH)₃₆ — Example 3 C₆₀(OSO₃H)₆ 9% 10⁻⁴Example 4 C₆₀(OSO₃H)_(x)(OH)_(y) 2% 10⁻⁵ Example 5 C₆₀(Ph-OH)₆ 2% 10⁻⁶Example 6 C₆₀(Ph-(OSO₃H)₆ 4% 10⁻⁴ Example 7 C₆₀(Ph-(OH)₂)₆ 3% 10⁻⁶Example 8 C₆₀(Ph-(OSO₃H)₂)₆ 7% 10⁻⁴ Example 9 C₆₀(SO₃H)₆F₁₅ 4% 10^(−3*)Example 10 Polymerized C₆₀(Ph-OH)₈ 3% 10⁻⁶

1. A producing method of a fullerene derivative, comprising the steps ofreacting a fullerene molecule with at least one halogen atom so as toproduce a halogenated fullerene; and reacting the halogenated fullerenewith a hydroxide or sulfite so as to produce a fullerene derivative,wherein one or more proton (H⁺) dissociative group is introduced into atleast one carbon atom of the fullerene molecule.
 2. A producing methodof a fullerene derivative according to claim 1, wherein the halogen atomis selected from the group consisting of a fluorine atom (F), a chlorineatom (Cl) and a bromine atom (Br).
 3. A producing method of a fullerenederivative according to claim 1, wherein the hydroxide is represented asMOH, and the sulfite is represented as M₂SO₃ (where M is an alkali metalatom).
 4. A producing method of a fullerene derivative according toclaim 3, wherein hydroxylated fullerene is obtained by the MOH, andsulfonated fullerene is obtained by the M₂SO₃.
 5. A producing method ofa fullerene derivative according to claim 4, whrein a hydroxyl group ofthe hydroxylated fullerene is further inverted into at least one of—OSO₃H and —OPO(OH)₂.
 6. A producing method of a fullerene derivativeaccording to claim 1, wherein the fullerene molecule is a sphericalcarbon cluster molecule Cm (m=any of 36, 60, 70, 76, 78, 80, 82 and 84,or a natural number capable of constituting a cluster molecule).
 7. Aproducing method of a fullerene derivative according to claim 1, whereinthe halogenated fullerene is reacted with the hydroxide or the sulfitein an organic solvent.
 8. A producing method of a fullerene derivativeaccording to claim 7, wherein the organic solvent with at least one ofcrown ether and a Lewis acid catalyst added thereto is used to react thehalogenated fullerene with the hydroxide or the sulfite.
 9. A producingmethod of a fullerene derivative according to claim 7, wherein at leastone of a phase-transfer catalyst and a Lewis acid catalyst is used toreact the fullerene derivative with the hydroxide or the sulfite in atwo-phase system of a solution of the hydroxide or the sulfite and theorganic solvent.
 10. A producing method of a fullerene derivativeaccording to claim 1, wherein the fullerene derivative is produced as aproton conductor.
 11. A producing method of a fullerene derivative,comprising the steps of: reacting a fullerene molecule with at least onehalogen atom so as to produce halogenated fullerene; and reacting thehalogenated fullerene with an aromatic compound having one or moreproton (H⁺) dissociative group by exchange reaction so as to produce afullerene derivative, wherein one or more aromatic group having one ormore proton (H⁺) dissociative group is introduced into at least onecarbon atom of the fullerene molecule.
 12. A producing method of afullerene derivative according to claim 11, wherein the exchangereaction is carried out in the presence of a Lewis acid catalyst.
 13. Aproducing method of a fullerene derivative according to claim 11,wherein the halogen atom is selected from the group consisting of afluorine atom (F), a chlorine atom (Cl) and a bromine atom (Br).
 14. Aproducing method of a fullerene derivative according to claim 11,wherein the proton dissociative group is selected from the groupconsisting of —OH, —OSO₃H, —COOH, —SO₃H and —OPO(OH)₂.
 15. A producingmethod of a fullerene derivative according to claim 11, wherein thefullerene molecule is a spherical carbon cluster molecule Cm (m=any of36, 60, 70, 76, 78, 80, 82 and 84, or a natural number capable ofconstituting a cluster molecule).
 16. A producing method of a fullerenederivative according to claim 11, wherein the aromatic compound or amixture of the aromatic compound and other solvent is used as a solvent.17. A producing method of a fullerene derivative according to claim 11,wherein the fullerene derivative is produced as a proton conductor. 18.A fullerene derivative, wherein one or more aromatic group having aproton (H⁺) dissociative group introduced into at least one carbon atomof a fullerene molecule.
 19. A fullerene derivative according to claim18, wherein the proton dissociative group is selected from the groupconsisting of —OH, —OSO₃H, —COOH, —SO₃H and —OPO(OH)₂.
 20. A fullerenederivative according to claim 18, wherein the fullerene molecule is aspherical carbon cluster molecule Cm (m=any of 36, 60, 70, 76, 78, 80,82 and 84, or a natural number capable of constituting a clustermolecule).
 21. A fullerene derivative according to claim 18, wherein thefullerene derivative functions as a proton conductor.
 22. A producingmethod of a polymerized fullerene derivative, comprising the steps ofreacting a fullerene molecule with at least one halogen atom so as toproduce halogenated fullerene; reacting the halogenated fullerene or aderivative thereof with a first aromatic compound having one or moreproton (H⁺) dissociative group and a second aromatic compound byexchange reaction so as to produce a fullerene derivative, wherein oneor more aromatic group of the first aromatic compound having one or moreproton (H⁺) dissociative group is introduced into at least one carbonatom of the fullerene molecule; and bonding a plurality of the fullerenederivatives obtained thereby to one another by one or more aromaticgroup of the second aromatic compound so as to produce a polymerizedfullerene.
 23. A producing method of a polymerized fullerene derivativeaccording to claim 22, wherein the exchange reaction is carried out inthe presence of a Lewis acid.
 24. A producing method of a polymerizedfullerene derivative according to claim 22, wherein the halogenatedfullerene or the derivative thereof is simultaneously reacted with thefirst aromatic compound and the second aromatic compound in a commonsystem.
 25. A producing method of a polymerized fullerene derivativeaccording to claim 22, wherein the halogen atom is selected from thegroup consisting of a fluorine atom (F), a chlorine atom (Cl) and abromine atom (Br).
 26. A producing method of a polymerized fullerenederivative according to claim 22, wherein the proton dissociative groupis selected from the group consisting of —OH, —OSO₃H, —COOH, —SO₃H and—OPO(OH)₂.
 27. A producing method of a polymerized fullerene derivativeaccording to claim 22, wherein the first aromatic compound is an arylcompound containing a single aromatic ring.
 28. A producing method of apolymerized fullerene derivative according to claim 22, wherein thefirst aromatic compound or a mixture of the first aromatic compound andother solvent is used as a solvent.
 29. A producing method of apolymerized fullerene derivative according to claim 22, wherein as thesecond aromatic compound, an aromatic compound represented by ChemicalFormula 3 is used.
 30. A producing method of a polymerized fullerenederivative according to claim 22, wherein the fullerene molecule is aspherical carbon cluster molecule Cm (m=any of 36, 60, 70, 76, 78, 80,82 and 84 or a natural number capable of constituting a clustermolecule).
 31. A producing method of a polymerized fullerene derivativeaccording to claim 22, wherein a large number of the fullerenederivatives are three-dimensionally bonded by one or more aromatic groupof the second aromatic compound so as to produce the polymerizedfullerene derivative.
 32. A producing method of a polymerized fullerenederivative according to claim 22, wherein the polymerized fullerenederivative is obtained as a proton conductor.
 33. A polymerizedfullerene derivative, wherein in a fullerene derivative, one or morefirst aromatic group having one or more proton (H⁺) dissociative groupis introduced in at least one carbon atom of a fullerene molecule, and aplurality of the fullerene derivatives are bonded to one another by asecond aromatic group so as to produce a polymerized fullerenederivative.
 34. A polymerized fullerene derivative according to claim33, wherein the proton dissociative group is selected from the groupconsisting of —OH, —OSO₃H, —COOH, —SO₃H and —OPO(OH)₂.
 35. A polymerizedfullerene derivative according to claim 33, wherein the first aromaticgroup is an aryl group containing a single aromatic ring.
 36. Apolymerized fullerene derivative according to claim 33, wherein thefullerene molecule is a spherical carbon cluster molecule Cm (m=any of36, 60, 70, 76, 78, 80, 82 and 84, or a natural number capable ofconstituting a cluster molecule).
 37. A polymerized fullerene derivativeaccording to claim 33, wherein the second aromatic group is an aromaticgroup represented by Chemical Formula
 4. 38. A polymerized fullerenederivative according to claim 33, wehrein a large number of thefullerene derivatives are three-dimensionally bonded by the secondaromatic group so as to produce the polymerized fullerene derivative.39. A polymerized fullerene derivative according to claim 33, whereinthe polymerized fullerene derivative functions as a proton conductor.40. A proton conductor, comprising: (1) a fullerene derivative as a maincomponent, wherein one or more aromatic group having one or more proton(H⁺) dissociative group is introduced into at least one carbon atom of afullerene molecule; or (2) a polymerized fullerene derivative wherein ina fullerene derivative, one or more first aromatic group having one ormore proton (H⁺) dissociative group is introduced in at least one carbonatom of a fullerene molecule, and a plurality of the fullerenederivatives are bonded to one another by a second aromatic group so asto produce the polymerized fullerene derivative.
 41. A proton conductoraccording to claim 40, wherein the proton dissociative group is selectedfrom the group consisting of —OH, —OSO₃H, —COOH, —SO₃H and —OPO(OH)₂.42. A proton conductor according to claim 40, wherein the aromatic groupor the first aromatic group is an aryl group containing a singlearomatic ring.
 43. A proton conductor according to claim 40, wherein thefullerene molecule is a spherical carbon cluster molecule Cm (m=any of36, 60, 70, 76, 78, 80, 82 and 84, or a natural number capable ofconstituting a cluster molecule).
 44. A proton conductor according toclaim 40, wherein the second aromatic group is an aromatic grouprepresented by Chemical Formula
 5. 45. A proton conductor according toclaim 40, wherein a large number of the fullerene derivatives arethree-dimensionally bonded by the second aromatic group to produce thepolymerized fullerene derivative.
 46. A proton conductor according toclaim 40, wherein the proton conductor substantially comprises thefullerene derivative only, or the fullerene derivatives bonded by abinder.
 47. An electrochemical device, comprising: a first electrode; asecond electrode; and a proton conductor sandwiched between the firstand the second electrodes, wherein the proton conductor comprises: (1) afullerene derivative as a main component, wherein one or more aromaticgroup having one or more proton (H⁺) dissociative group is introducedinto at least one carbon atom of a fullerene molecule; or (2) apolymerized fullerene derivative wherein in a fullerene derivative, oneor more first aromatic group having one or more proton (H⁺) dissociativegroup is introduced in at least one carbon atom of a fullerene molecule,and a plurality of the fullerene derivatives are bonded to one anotherby a second aromatic group so as to produce the polymerized fullerenederivative.
 48. An electrochemical device according to claim 47, whereinthe proton dissociative group is selected from the group consisting of—OH, —OSO₃H, —COOH, —SO₃H and —OPO(OH)₂.
 49. An electrochemical deviceaccording to claim 47, wherein the aromatic group or the first aromaticgroup is an aryl group containing a single aromatic ring.
 50. Anelectrochemical device according to claim 47, wherein the fullerenemolecule is a spherical carbon cluster molecule Cm (m=any of 36, 60, 70,76, 78, 80, 82 and 84, or a natural number capable of constituting acluster molecule).
 51. An electrochemical device according to claim 47,wherein the second aromatic group is an aromatic group represented byChemical Formula
 6. 52. An electrochemical device according to claim 47,wherein a large number of the fullerene derivatives arethree-dimensionally bonded by the second aromatic group to produce thepolymerized fullerene derivative.
 53. An electrochemical deviceaccording to claim 47, wherein the proton conductor substantiallycomprises the fullerene derivative only, or the fullerene derivativesbonded by a binder.
 54. An electrochemical device according to claim 47,wherein the first electrode and the second electrode are gas electrodes.55. An electrochemical device according to claim 54, wherein theelectrochemical device is configured as a fuel cell.
 56. Anelectrochemical device according to claim 54, wherein theelectrochemical device is configured as a hydrogen-air cell.
 57. Anelectrochemical device according to claim 47, wherein either the firstelectrode or the second electrode is a gas electrode.
 58. Anelectrochemical device according to claim 47, wherein at least one ofthe first electrode and the second electrode is an active materialelectrode. (CHEMICAL FORMULA 3)

(WHERE n IS AN INTEGER SELECTED FROM THE RANGE FROM 0 TO 5, AND Ar¹ ANDAr² ARE SUBSTITUTED OR UNSUBSTITUTED ARYL GROUPS WHICH ARE THE SAME ASOR DIFFERENT FROM EACH OTHER.) (CHEMICAL FORMULA 4)

(WHERE n IS AN INTEGER SELECTED FROM THE RANGE FROM 0 TO 5, AND Ar^(1′)AND Ar^(2′) ARE SUBSTITUTED OR UNSUBSTITUTED AROMATIC GROUPS WHICH ARETHE SAME AS OR DIFFERENT FROM EACH OTHER.) (CHEMICAL FORMULA 5)

(WHERE n IS AN INTEGER SELECTED FROM THE RANGE FROM 0 TO 5, AND Ar^(1′)AND Ar^(2′) ARE SUBSTITUTED OR UNSUBSTITUTED AROMATIC GROUPS WHICH ARETHE SAME AS OR DIFFERENT FROM EACH OTHER.) (CHEMICAL FORMULA 6)

(WHERE n IS AN INTEGER SELECTED FROM THE RANGE FROM 0 TO 5, AND Ar^(1′)AND Ar^(2′) ARE SUBSTITUTED OR UNSUBSTITUTED AROMATIC GROUPS WHICH ARETHE SAME AS OR DIFFERENT FROM EACH OTHER.)